Autoloader is meant to be a streaming dataframe/table or just write directly into a table with a once=True option (single batch process). So really you want to autoload each source into their own tables then join them together in later logic if thats required. Autoloader can be set to inferSchema or have a rescue column if the schema ever chabges (sounds like they remain fixed in your case). So look for examples that use that once=true option and the .saveAsTable("<catalog.schema.table>") option. Let me know if you have any issues still.